The present invention relates to heavy duty shears of the type mountable on the boom of a mobile machine such as a backhoe and, more particularly, to improvements in connection with the cutting and piercing tip portion of the shearing jaws of such heavy duty shears.
Heavy duty shears of the type to which the present invention is directed are well known in conjunction with the handling and shearing of a wide variety of scrap materials including, for example, iron and steel pipes of various diameters, metal rod of various cross-sectional configurations and diameters, I-beams, channels, angles, and other structural metal components, as well as a variety of other metal and non-metal materials and material configurations. Generally, the shear head includes a supporting structure by which the head is adapted to be attached to the boom of a mobile machine such as a backhoe, and the shearing components or jaws are relatively pivotal and powered by a hydraulic piston and cylinder arrangement or arrangements actuated through the hydraulic system of the support vehicle. The relatively pivotal jaw components are provided with blade inserts providing cutting edges which are cooperable to shear a workpiece therebetween during displacement of the jaw components between open and closed positions relative to one another and, in many instances, the distal end of one of the jaw members is provided with a cutting and piercing tip arrangement by which a workpiece is pierced and severed during closure of the one jaw member relative to the other. Various prior art shears of the foregoing character are illustrated, for example, in U.S. Pat. No. 4,670,983 to Ramun, et al.; U.S. Pat. No. 4,776,093 to Gross; U.S. Pat. No. 5,187,868 to Hall; and U.S. Pat. No. 5,230,151 to Kunzman, et al., all of which patents are incorporated herein by reference for background information.
In heavy duty shears of the foregoing character which have cutting and piercing tip arrangements, the tip includes a piercing edge and a cutting edge or edges at right angles to the piercing edge and which piercing and cutting edges are respectively parallel to and perpendicular to the pivot axis of the jaw member on which the tip is provided. The other jaw member of the shear is provided with blade inserts providing linear cutting edges which are positioned for cooperable shearing relationship with the piercing and cutting edges of the tip of the one jaw member during relative pivotal displacement of the jaw members to a closed relationship relative to one another. The piercing and cutting edges of the tip are cooperable with the cutting edges of the blade inserts to pierce and sever a metal workpiece therebetween, and it will be appreciated that such jaw tips are subject to extreme wear and accordingly require frequent replacement. Replacement of the tips is expensive both from the standpoint of the cost of the tip component and the down time required to remove, repair and replace a damaged or worn tip component or, if beyond repair, to replace with a new tip component. In shearing apparatus heretofore available, the piercing and cutting tip component has been of a structural configuration or profile limiting the piercing and cutting edges to a single piercing and cutting edge configuration relative to the jaw member on which the tip is mounted. Accordingly, repair or replacement of the tip is required each time the piercing and cutting edges become worn or damaged, whereby maintenance costs and down time is undesirably high.